1. Field of the Invention
The present invention generally relates to a speech synthesizing apparatus, and more specifically, to such a speech synthesizing apparatus capable of synthesizing speech from text.
2. Description of the Prior Art
As shown in FIG. 1, a speech synthesizing apparatus 1 performed by the rule synthesizing system has been proposed as the conventional speech synthesizing system for synthesizing text containing sentences mixed with Katakana characters and Kanji characters, as described in Japanese Laid-open Patent Application No. Hei-5-94196 in 1994.
In this speech synthesizing apparatus 1, a series of characters inputted from a text input function block 2A of a sentence analyzing unit 2 is analyzed with reference to a dictionary function block 2C in a text analyzing function block 28, and Japanese syllabary, word, phrase boundary and also basic accent are detected in a detection function block 2D. The detection result of the sentence analyzing unit 2 is arranged as a series of phoneme symbols 3B in accordance with a predetermined phoneme rule in a phoneme rule block 3A of a speech synthesizing rule unit 3, and then supplied to a phoneme control parameter generating block 3C. Similarly, the detection result is arranged as a series of phrase, accent and pauses 3 E in accordance with a predetermined rhythm rule in a rhythm rule block 3D, and thereafter is given to a rhythm control parameter generating block 3F.
In the phoneme control parameter generating block 3C and the rhythm control parameter generating block 3F, a speech reading speed is designated by a speed instruction issued from a speed instruction generating unit 4, and then a synthesizing parameter 3G having this speech reading speed and a basic pitch pattern 3H having this speech reading speed are produced. These synthesizing parameter 3G and basic pitch pattern 3H are supplied to a speech synthesizing filter block 5A of a speech synthesizing unit 5.
Thus, a speech synthesizing filter block 5A produces a synthesized speech output 5B, resulting in the final as an output of the speech synthesizing apparatus 1.
In such a conventional speech synthesizing apparatus 1, when either rapid (speed) reading, or head searching is carried out, the speed instruction of the speed instruction generating unit 4 provided outside this speech synthesizing apparatus 1 is varied by means of a software parameter, or a hardware member such as a variable resistor, so that the generation speeds of the synthesizing parameter 3G and the basic pitch pattern 3H in the phoneme control parameter generating block 3C and the rhythm control parameter generating block 3F are controllable.
However, the above-described conventional speech synthesizing method, is problematic. When the rapid reading is performed by increasing the reading speed of the text, this reading speed cannot be increased higher than a speed corresponding to the limit values of the signal processing speeds with respect to the sentence analyzing unit 2, the speech synthesizing rule unit 3 and the speech synthesizing unit 5. Moreover, a lengthy searching time is required.
Also, to perform head searching, the information required for the search, (e.g., indexes of phrases) which has been previously prepared for text inputted into the text input block 2A, must be input. As a result, a very cumbersome process is needed outside the speech synthesizing apparatus 1. This presents another problem that a large-scaled speech synthesizing system must address.